Insulation Grams, Demystified
A field-tested guide to choosing the right warmth for your workload — covering 40g, 60g, 80g, 100g, 150g, and 200g synthetic insulation, with temperature ranges, mission-fit recommendations, and the OTTE jackets built around them.
40g for active movement in cold. 100g for most cold-weather tasks. 200g when you’re static in deep cold.
Synthetic insulation is rated by grams per square meter (g/m²). More grams means more loft, more warmth, and more bulk. The temperature ranges below assume a moisture-managing base layer underneath and a wind-blocking shell on top — remove either and the numbers don’t hold.
Most insulation guides skip the part operators actually need: how grams translate to mission. This one doesn’t.
If you’ve ever stood next to a buddy in matching kit and one of you was sweating while the other was shivering, you already know the truth about insulation: temperature ratings are only half the answer. The other half is what your body is doing inside the jacket. Sit still and 100g feels thin. Move hard and the same 100g feels like a sauna. The grams don’t change — the workload does.
This guide gives you both halves. We’ll start with the temperature ranges most people are actually searching for, then explain why those numbers aren’t the whole picture, then map specific grammages to specific missions and the OTTE pieces built around them.
The Insulation Temperature Chart
Here’s what the grams actually mean in degrees, assuming you’re wearing a moisture-managing base layer and have a wind-blocking shell available. Active ranges assume sustained movement (patrolling, hiking, range work). Static ranges assume minimal movement (overwatch, glassing, stand hunting, vehicle crew).
| Insulation Weight | Active Range | Static Range | Best For | OTTE Match |
|---|---|---|---|---|
| 40gPer m² | 35°F to 55°F | 45°F to 60°F | High-output movement, active layer, transitional cool weather | PrimaLoft® Active+Active Insulation → |
| 60gPer m² | 25°F to 45°F | 35°F to 50°F | Mid-output movement, fall hunting, urban shoulder season | Industry reference — not in OTTE line |
| 80gPer m² | 15°F to 35°F | 25°F to 45°F | Mixed-output cold, classic hunting jackets | Industry reference — not in OTTE line |
| 100gPer m² | 10°F to 30°F | 20°F to 40°F | Most cold-weather tasks — the do-everything weight | PrimaLoft® GoldLV Insulated Hoody → |
| 150gPer m² | 0°F to 20°F | 10°F to 30°F | Heavy mid-layer, low-output cold, mountain hunting | Industry reference — not in OTTE line |
| 200gPer m² | -10°F to 15°F | -20°F to 20°F | Static cold, deep winter overwatch, deer stand, vehicle crew | PrimaLoft® GoldHT Insulated Parka → |
Why The Chart Alone Will Get You In Trouble
Picking insulation by air temperature alone is the most common mistake in cold-weather kit selection. It’s the reason hunters freeze in $400 puffies and patrol guys overheat in 100g hoodies. Temperature is one variable. Workload is another. Wind is a third. Wet is a fourth. All four matter.
Your body produces heat in proportion to how hard it’s working. A guy walking flat at 3 mph in 30°F generates a fraction of the heat that the same guy generates patrolling uphill with a ruck. Same temperature. Different problem. The patroller in 200g will roast within 15 minutes — and once he sweats through his base layer, that 200g of loft becomes a wet sponge that conducts heat away from his body faster than it traps it.
The shorthand we use:
- Moving hard? Run lighter than the temperature suggests. 40g to 100g with a wind shell on top almost always beats a heavy puffy when output is high. Vent early, peel layers when you stop.
- Slowing down or static? Step up. 100g to 200g with a hard shell on top so the loft stays dry and wind can’t flatten it.
- Wet conditions? Synthetic over down. Synthetic insulation keeps roughly 80–90% of its warmth when wet. Down loses nearly all of it. This is non-negotiable for tactical and field use.
- Cold and windy? Wind matters more than air temp below 40°F. A 20 mph wind at 25°F feels like 8°F to your skin. Always have a shell available.
If you only remember one thing: insulation traps heat your body produces. It doesn’t generate heat. If your body isn’t producing enough — because you’re static, or because the cold is extreme — you need more grams. If your body is producing too much, more grams will hurt you.
Insulation By Mission Profile
Air temperature alone won’t tell you what to wear. Mission profile will. Here’s how the grams map to the work.
Static Overwatch
Long durations of minimal movement. Glassing, surveillance, stand hunting, sniper hide. Heat retention is the only metric that matters.
Patrol & Movement
Sustained walking with mixed terrain and pace changes. The variable-output mission. You need warmth at halts and breathability on the move.
Active Range Day
Cold-weather shooting, drills, repositioning. High-output bursts with cold halts in between. Bulk slows you down on the gun.
Vehicle Crew & Standoff
Static for hours in cold metal. Heater works until it doesn’t. Same heat retention problem as overwatch but with armor compatibility on top.
Cold-Weather Hike & Glass
The hunter’s dilemma. You hike in hot, sit cold for hours, then maybe move again. Layering system matters more than any single piece.
Urban Shoulder Season
Cool mornings, mild afternoons, indoor heat. Need a piece that disappears under a shell or works as outerwear on its own.
PrimaLoft 101: Why The Brand Spec Matters
Most quality synthetic insulation in tactical and outdoor apparel is some form of PrimaLoft. It’s the reference standard, and there’s a reason: PrimaLoft was originally developed in the 1980s under a U.S. Army contract that asked for a synthetic alternative to down that would actually work when soaked. They got it.
The two grades you’ll see most often in tactical apparel are PrimaLoft Gold and PrimaLoft Active+:
PrimaLoft Gold
The flagship. Highest warmth-to-weight ratio of any synthetic insulation on the market — comparable to 550–600 fill down by weight, but it retains roughly 96% of its warmth when wet. This is what fills the LV Insulated Hoody (100g) and the HT Insulated Parka (200g). When you see PrimaLoft Gold in a spec sheet, you’re looking at the best synthetic loft money can buy in that weight class.
PrimaLoft Active+
Designed for output. Active+ is engineered with higher air permeability so warm air doesn’t get trapped during high-exertion work — meaning it dumps heat faster when you’re moving and reduces the swing between “cold at halts” and “swimming in sweat on the move.” This is the insulation you want in a 40g active layer.
What the brand spec gets you that generic synthetic doesn’t
Generic polyester insulation tends to compress permanently after 50–100 wash cycles. Loft collapses, warmth drops, the jacket gets thinner every season. PrimaLoft Gold maintains roughly 90%+ of its loft after 100 cycles. Over the working life of the jacket, that’s the difference between a $300 piece that’s still doing its job in year five and one you replace every two seasons.
The OTTE Insulation Lineup
OTTE’s insulated line is built around the three weights that cover roughly 90% of cold-weather tactical work: 100g for the do-everything middle, 200g for static deep cold, and the Patrol Parka shell on top of either when wet or windy. Here’s how each piece earns its place.
LV Insulated Hoody
If you can only own one insulated jacket, this is the weight to own it in. 100g PrimaLoft Gold across the body covers most cold-weather tasks — patrol, range, fall and winter movement — with enough warmth at halts and enough breathability to layer under a shell when wet.
- Insulation: 100g PrimaLoft® Gold
- Shell: Patriot Lite with DWR finish
- Reinforcement: Internal 200D MultiCam® sidearm-abrasion patches
- Hood: Climbing-inspired, four internally-routed drawcords
HT Insulated Parka
Built for static cold — deer stands, range halts, vehicle crew, overwatch. 200g PrimaLoft Gold traps heat even when wet. Patriot Lite shell with DWR sheds sleet and light snow. Cut relaxed for layering over a midlayer, plate carrier, or both. Tested down to -20°F.
- Insulation: 200g PrimaLoft® Gold
- Shell: Patriot Lite with DWR, 200D MultiCam® abrasion panels
- Cut: Relaxed for layering, drop-tail hem
- Hood: Adjustable with stiff brim for clear vision
The Shell Pairings
No insulation works without a shell strategy. Wind strips warmth faster than dropping air temperature. Wet collapses loft from the outside. The two pieces below pair with anything in the OTTE insulated line.
Rambler Windbreaker
A featherweight wind-blocking shell that lives in your pocket until you stop moving. Pairs perfectly with 40g–100g insulation when output is high and conditions are dry but breezy.
Shop Rambler →
OG Recce Jacket
Wind-blocking, water-resistant outer layer that goes over any of the insulated pieces when conditions get wet or seriously windy. The shell that protects your loft.
Shop The Recce →Field Rules That Will Save Your Loft
Even the right grammage won’t save you if you’re abusing the jacket. These are the habits that separate a piece that performs for ten seasons from one that’s done in two.
- Vent early, vent often. Use front zips, cuffs, and hems to dump heat before you sweat. Wet loft is dead loft. Once you’ve sweated through your base, the jacket is working at half capacity.
- Wash by the label, revive the DWR. Shell fabrics shed water through a Durable Water Repellent finish. When water stops beading and starts wetting through, the shell breathes worse and conducts heat away faster. Wash gentle, revive with a spray-on or wash-in DWR every season.
- Store dry, store uncompressed. Don’t leave insulation stuffed at the bottom of a pack between seasons. Hang it or store it loose. Permanent compression kills loft and there’s no fixing it.
- Field-dry under a shell. If your insulation gets wet on a multi-day, the worst thing you can do is take it off in cold air. Layer a shell over it, keep moving (low output), and let body heat drive moisture out.
- Match the cut to the layer order. If you plan to wear the insulated piece over base + fleece + maybe armor, size it relaxed. If it’s the outer layer worn over a base only, size it trim. Same jacket. Two different jobs.
Frequently Asked
For most active winter use down to about 10°F, yes — with a moisture-managing base layer underneath and a wind-blocking shell available. 100g PrimaLoft Gold is the do-everything weight for cold-weather work where output varies. If you’ll be static for hours below 20°F, step up to 200g.
60g insulation handles roughly 25°F to 45°F when you’re moving, and 35°F to 50°F static. It’s a mid-output cold weight — common in fall hunting jackets and shoulder-season urban pieces. For tactical use, OTTE skips this weight in favor of 40g (active layer) and 100g (do-everything), which together cover the same range with less ambiguity.
40g PrimaLoft Active+ handles roughly 35°F to 55°F when you’re moving, and 45°F to 60°F static. It’s an active layer designed to be worn during high-output work without overheating, and it pairs with a wind shell for the colder end of that range.
Choose 200g for static missions or extended exposure below freezing where heat retention beats breathability. Deer stand, overwatch, vehicle crew, range halts in deep winter. 200g is too much for sustained movement in most conditions — you’ll sweat through it within 20 minutes of hard work.
Start with workload, not temperature. Moving hard? 40g–100g. Slowing down or static in cold? 100g–200g. Then check the temperature range against the chart above and adjust by one weight up if you’ll be static for long periods, or one weight down if output will be high. Always have a wind-blocking shell available regardless of grammage.
For tactical and field use where wet weather is realistic, yes. Down loses nearly all its insulating value when wet. PrimaLoft Gold retains roughly 96% of its warmth when wet. Down is lighter and packs smaller, but if there’s any chance of getting soaked, the synthetic wins on capability. This is why the U.S. military spec’d the original PrimaLoft contract in the 1980s.
For wind or wet, yes. Wind strips heat from insulation faster than dropping air temperature does — a 20 mph wind at 25°F feels like 8°F to your skin. A wet shell collapses loft from the outside. Always have either a hard shell (for wet/windy) or a featherweight wind layer (for dry, high-output) available with any insulated piece.